Arylamino-1-hydroxy-naphthalene-2-carboxylic acids



Patented Jan. 16, 1934 STATES PATENT OFFICE I ARYLAMINO-l-HYDROXY NAPHTHALENE 2-CARBOXYLIC' ACIDS Leopold Laska and Oskar Haller, Offenbach-onthe-Main, Germany, assignors to General Aniline Works, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application February 23, 1933, Serial No. 658,241, and in Germany February 4 Claims.

wherein R stands for a radical of the benzene series.

The process in accordance with this invention consists in heating with carbon dioxide, at a raised pressure, an alkali metal salt of 1-hydroxynaphthalene containing in 5-, 6-, '7- or 8- position an aryl-arnino-group.

The carboxylic acids, thus obtained, exhibit intense colorations when their alcoholic solutions are mixed with a ferric chloride solution. By reason of these properties, the carboxylic acid group is assumed to have entered the orthoposition to the hydroxy group.

The following example serves to illustrate the invention, but it is not intended to limit the invention thereto, the parts being by weight:

235 parts of 1-hydroxy-7-phenylaminonaphthalene are dissolved in 56 parts of potassium hydroxide and 1000 parts of water in an autoclave provided with a stirrer; the water is then distilled under reduced pressure until the potasslum salt obtained is completely dried. After boxylic acid may be further purified by dissolving.

it in sodium acetate solution and precipitating it therefrom by means of an acid. It crystallizes from xylene or dichlorobenzene, has a yellow color and melts at 199 C. It gives in dilute alcoholic solution a green coloration on the addition of a few drops of dilute ferric chloride solution.

By reason of these properties, the carboxylic acid is assumed to be the 7-phenylamino-1-hydroxynaphthalene-2-carboxylic acid which corresponds to the following formula:

OH @NH COOH The reaction may be carried out in the same manner by using the sodium salt of 7-phenylamino-l-hydroxynaphthalene.

The following table shows the properties of some other arylamino-1-hydroxy-naphthalene- 2-carboxylic acids which may be prepared according to the present invention:

Coloratifim w on Recrystallized Melt mixed C0101 mg from oint with p ferric chloride solution 7 p tolylamino Yellowish- Ohloroben- 203 0. Dark 1 hydroxynaphgreen powzone green thalene 2 carder boxylic acid 6 phenylamino Colorless crys- Dichloroben- 185 C. Violet l hydroxynaphtals zene thalene 2 carboxylic acid 6 p tolylamino Colorless crys- Ohloroben- 199 0. Violet 1 hydroxynaphtals zene thalene 2 carboxylic acid 5 phenylamino Yellow pow- Chlorobcn- 198 C. Green 1 hydroxynaphder zene tlialene 2 carboxylic acid 5 p tolylamino Brownish-yel- Chloroben- 188 C. Green 1 hydroxynaphlow powder zene thalene 2 carboxylic acid 8 phenylamino Yellow lcaf- Ohloroben- 185 0. Blue l-hydroxynaphlets zone thalene 2 carboxylic acid We claim:

1. The arylamino-l-hydroxy naphthalene-2- carboxylic acids of the general formula:

wherein R stands for a radical of the benzene series, which compounds have a definite melting point, are soluble in alkalies and exhibit intense colorations when their alcoholic solutions are mixed with a dilute solution of ferric chloride.

2. The 7-phenylamino-1-hydroxynaphthalene- 2-carboxylic acid of the following formula:

011 ONE GOOH COOII which compound melts, when recrystallized from chlorobenzene, at 199 C., is soluble in alkalies and exhibits a violet coloration when its alcoholic solution is mixed with a dilute solution of ferric chloride.

4. The 5-phenylamino-l-hydroxynaphthalenez-carboxylic acid of the following formula:

which compound melts, when recrystallized from chlorobenzene, at 198 0., is soluble in alkalies and exhibits a green coloration when its alcoholic solution is mixed with a dilute solution of ferric chloride.

LEOPOLD LASKA. OSKAR HALLER. 

